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216           MOBPHOLOGY AND EVOLUTION
above downwards and also becomes continuous with the circular fibres of the stomach. At the lower end of the oesophagus it forms the sphincter of the cardia, which is two inches long. The inner longitudinal fibres in the upper part consist of a few strands, and the submucosa bulges between them ; they are entirely absent in the lower part of the oesophagus, ilan has only two muscular coats. The folds of the mucous membrane extend throughout the tube in the Gibbon, but they are restricted to its lower end in the Gorilla, according to Deniker (44).
The Stomach.
In the Chimpanzee the oesophagus passes through the diaphragm at the level of the ninth dorsal vertebra, and opens into the stomach after an intra-abdominal course of half an inch. The sfeomach is divided into fundus, body, antrum, and pylorus. The fundus is well marked and projects up into the left cupola of the diaphragm. The long axis of the stomach is crescentic, and is more horizontal than in Man, The great curvature reaches a point half an inch below the fourth lumbar vertebra, and the lowest point of the lesser curvature is level with the first lumbar vertebra. Consequently the stomach is U-shaped, and the pylorus is not far from the oesophagus. The pyloric antrum is one and a half inches long, and the pylorus, whose walls are thick, is of the same length. Between the antrum and pylorus there is a slight incisura, and there is a sudden transition from the pylorus to the duodenum. The pylorus does not project like a knob into the duodenum as it does in Man.
The serous coat is a uniform covering, united in the usual manner to the omenta. The muscles are thin, but